Introduction: R/C Steam Turbine Tank
Seriously though, if you want something outside of the norm, something part geeky, part artsy, and full on FUN, then this might be the project for you. And yes, it really does run on STEAM, and yes, it is a TURBINE.
Before we get started, here comes the disclaimers.... You are reading this because you like making things, hacking things to make it better, or make something that doesn't exist. Therefore you are probably a pro at voiding warranties, and have a tendency to ignore warnings... but since I am giving you exact details of how to build this thing, humor me and please read the following carefully, so that I can sleep at night!
Steam power should not be taken lightly. This is instructable contains detailed instructions on building a R/C machine that is carrying flammable gas, and on fire, and producing steam pressure capable of scalding, or worse. Without proper attention, you can suffer blisters on your finger - no big deal, or burn down your house - BIG deal. Just be careful, and make sure that your r/c gear is working properly before lighting it up, and never tweak the boiler's safety valve.
Now with that out of the way, here's a project that can be very fulfilling to build, and fun to run. Your friend has a cool R/C toy car, but you've got a R/C steam turbine tank.
On with the build!
Step 1: Tools
Ready to jump in? Here are the tools you need....
Fire Extinquisher, Face Mask, Safety Goggles, Gloves
-Hex Wrenches in Metric and Standard
-Wrench & Needle Nose Pliers
-Dremel flexible neck a plus
-Dremel grinder discs
-Dremel sanding wheels
-Soldering / Brazing Torch
-Small Zip Ties
Materials (described in detail later, in the steps):
-CEN universal joint
-Steel rods, 4mm
-Meccano sprockets - 1 large, 3 small
-Meccano Chains, less than 2 feet
-Aluminum sheets & rods
-Shaft couplings & lock couplings
-Nuts, bolts, screws, washers etc.
-High Heat Paint
Step 2: Main Components: the Steam Power Plant
The Steam Engine:
Jensen is the last American toy/model live steam engine company, they've been around for over 70 years. Jensen has been a great supporter of my work, including donating engines to my Steam Armatron project, just because they wanted me to do something cool with their products :)
Recently they took a big risk by producing a steam turbine, instead of the usual steam piston engines that's usually associated with live steam. The result was their impressive Model 95G turbine steam plant. I was able to get my hands on these steam turbines as stand alones, without having to purchase the entire plant. Jensen is currently not selling the turbine by themselves - you have to purchase the entire steam plant. However, seems like there is enough of a demand for it to make it worth their while... so if you are serious about this project, or other mobile turbine related projects, let me know! I am gathering a list together to show Jensen how much of a market is out there for stand alone turbines :)
With the high demand of a turbine engine, you need a very powerful steam boiler. I use mainly Cheddar brand boilers for most of my RC Steam Contraptions. Cheddar flue boiler have lots of cross tubes and produces steam very quickly. They come with safety valve, pressure gauge, sight glass, wood plank insulation, pipes and fittings. Unfortunately Cheddar is no longer in business, they are now part of the Stuart Models, a super high end line of engines, and have not yet re-release the Cheddar line.
I get most of my Cheddars through ebay and trading with steam hobbyist friends. However there are other model steam boiler available, such as these, or these. Just make sure that you use a gas fired flue boiler, and not a toy pot boiler. Steam Turbines uses up a lot of steam very quickly, so the boiler needs to be able to produce and maintain around 20psi of pressure.
Burner & Fuel:
Cheddar boilers come with ceramic burners, and attachment for disposable gas tanks. These gas tanks are the ones used for camping stoves, and contain 70% butane, 30% propane. Do not use gas other than what the manufacture of the boiler recommends.
Step 3: Main Components:The Chassis
For the chassis, I used a Kyosho Nitro Blizzard. The reason for using this particular chassis, is because I wanted a treaded steam turbine vehicle, and this was the only chassis available with a forward and reversing clutch, used with a nitro engine. Turbines only spin in one direction, unlike steam piston engines that can reverse.
Kyosho Blizzard uses disc brakes on the differentia for skid steering. Basically it uses a servo to stop one side of the track from moving, to perform steering.
Blizzards are not cheap toys, but a high quality RC machine. I got this from ebay, in used condition, much cheaper than a brand new one. If you go with this cheaper route, make sure that the chassis and mechanics are in working order. You will save some money if you look for one with engine problems - the nitro engine will not be used for this project.
Kyosho also make an electric version of the Blizzard, which has no clutch for forward/reverse (electric motors can spin in both directions). Make sure that use the "Nitro" version for this build. A picture of the box is provided for the Nitro version below.
Step 4: Main Components: Radio Control
For RC, you don't need anything fancy. Any 2 Channel surface radio will do the job, either the pistol type or stick type. You need a transmitter (TX) and a receiver (RX), and a 4AA battery pack. If you purchase a package system, you'll get all of these, and probably some servos as well.
If you are not familiar with Radio Control (RC or R/C),
here is a quick overview of radio systems.
Notes about Frequency:
Take special note of the frequency - use only 27 megahertz, or 75 megahertz, they are for ground use. The exception is 2.4 Ghz system, which binds a particular receiver, to a particular transmitter, and are glitch free.
72 megahertz is for aircraft only. If someone nearby crashed their expensive r/c helicopter because you turned on your transmitter using the same frequency, you'd better hope that he doesn't find you.
Different frequencies uses special crystals, which are just little tiny things that you plug into your transmitter and receiver, that allows your receiver to listen to your the commands of your transmitter. They must match, and must be made for the mhz that you are using.
2.4GHz Spread Spectrum:
For my turbine tank I used a Spektrum DX6. Spektrum uses 2.4GHz spread spectrum technology, that doesn't need crystals, because you "bind" you receiver to your transmitter, and it will not be interfered with other radio systems. Going with 6 channels is over kill for this particular project, but I already have it, because needed a radio system that I can run all of my steambots (one of them uses all 6 channels). It is especially important at events such asRoboGames & Maker Faire, where there are a lot of radio interference, and chances of someone mistakenly using your channel is pretty high. I also didn't want to take the chance of interfering with someone else's robots in the middle of combat, or have someone else's transmitter drive my steambots into the wall :)
You will also need 2 servos... which will be described in more detail later.
Step 5: Removing the Nitro Engine
Kyosho Nitro Blizzard comes as a kit new, so it's made to be easily put together, which means it's easy to take apart as well. I received my Blizzard used, so I had to remove the engine. Just a handful of screws and it detaches easily. If you get the kit, then you need to put the chassis together, including the differentials and clutch.
Step 6: Attaching Shaft Adapters
This lengthy step describes how to attach Meccano Sprockets to the turbine engine, and the Blizzard clutch.
I use a lot of older Meccano, or Erector Set parts for my steam machines, in particular
lots of Meccano sprockets. Sprockets and chains are a bit easier to test gear ratios than gears, because you can quickly swap out different size ones, and change the chain length to test the best gear ratio for your particular contraption. Sprockets and chains are also more forgiving, so if you are like me and can't drill a straight hole to save your life, then building a gearbox where gears have to line up perfectly, is way beyond my abilities. The downside of sprocket/chain system is that they can derail easily if not set up correctly (which will be explained in later steps).
So for the turbine to drive the treads, I knew that I wanted to meccano sprockets and chains, but the problem is that meccano sprockets fits shafts that are roughly 4mm in diameter, and the tubine and clutch shafts are slightly larger.
So without having any machining skills, I had to rely on parts that I can hack and use. I found these really useful shaft adapters from my local hobby store about a year ago, and have been using lots of them for my builds. They are made by CEN, and the stock number is WS009. On one end is a smaller diameter hole than the other end, with set screws of lock the shafts in place. These CEN universal joints come in 2 sizes, these are the larger ones and fits perfectly with this setup.
With the CEN adaptor on one end, and a 4mm shaft from the hobby store, I was able to attach the sprocket to the turbine, and another set for the clutch. Thread locker was used to secure the hex set screw. Anything that suffers a lot of vibration is probably a good idea to use a thread locker. I used Tamiya brand thread lock because I had it laying around, but any brand of removable thread lock will work.
Step 7: Mounting the Steam Turbine
Figuring out how to attach the turbine was fairly straight forward. I was not certain how much gearing I'd need, so I made some space allowances for additional gearing down if needed. First test was a simple mounting the turbine on a piece of scrap wood, and mounting that on the chassis. I tried 1:1 ration from the turbine to the clutch, and tested it with an air compressor (will explain testing with an air compressor in later steps). It needed to be geared down as suspected.
After determining that the is a good placement of the turbine, I proceeded to mount it to the chassis for good.
You need to extend the chassis slightly to make space for the turbine and sprockets. I used [K&S Aluminum sheets for the base, but you can use any sheet metal that is thick enough to be sturdy, but not too heavy. Cut the aluminum to size with a Dremel tool, and drill mounting holes on the mount and the chassis, using some of the original holes. Thread lock to secure the base.
Step 8: Sprocket Shaft Bracket
This step describes how to make the U shaped bracket to support the 2 Sprockets needed to gear down the turbine engine to the clutch
Making the bracket to support the sprocket shafts was fairly easy. You just need some sort of a bracket where the sprocket shaft can spin easily without much friction.
I used aluminum because it's light, and easy to bend. You can find all sorts of sizes and shapes at your local hardware store. Using a Dremel tool with grinder wheel, you can cut the soft aluminum easily. After cutting the desired length, you can clamp it to a table vice and bend it by hand. Drilling is also easily done with a power drill. I found these flanged shaft collars laying around, sorry but I have no idea where or which R/C vehicle it came from. You just need something that is slightly larger than the shaft, that provides smooth rotation. Drill a hole about the size of the collar, and push, or gently hammer the collar in. Test the alignment by sliding a 4mm shaft in, to insure that it is lined up and turns smoothly.
Drill the bracket's base and corresponding holes on the chassis. Mount the bracket onto the chassis with a couple of nuts and bolts.
Step 9: Assembly of the Sprockets and Chains
This step shows the process of putting together the sprockets and chains gear reduction system
Slide the 4mm shaft through on side, and slide in the big and small Meccano sprockets, then push the shaft out the other side of the bracket. Line up the sprockets to the corresponding sprockets that it will be attached to via the chain, but don't tighten the set screws yet.
With a pair of needle nose pliers, you can easily open and close the Meccano chains. Make the desired length of chain needed for both sets. Sprocket chain must not be too tight, otherwise it will cause too much friction and reduce the performance, or stall the engine completely. It should not be too loose either, or it will derail. You could add idler wheels to insure the right amount of tension (like on a bicycle), but I was too lazy to make something that fancy.
After a desired length of chain is chosen, loop around the sprockets and close the link with your needle nose pliers. give it a quick test by hand spinning it by hand. It should feel smooth. If it is too tight you will have a hard time spinning it. If it is too loose, the chain will derail if you spin it pretty fast. Add or take out one link at a time, until both sets spin easily.
Double check that both sets of sprockets and chains are lined up, and on the same plane. Secure the sprockets with the set screw - thread lock is strongly recommended as these parts will be spinning very fast and can come loose.
The ends of the shafts need to be held in place by lock collars. You can find lots of them at your local R/C hobby stores, you can find in just about any size. Make sure that you have a washer in between, and might be a good idea to add a drop of ball bearing oi, or other light oil to it, as well as the chains and sprockets.
Step 10: Testing With an Air Compressor
Now with the gearing finished, it's time to test this puppy out!
Testing steam engines with an air compressor
Here is an useful piece of equipment to test out steam engines. Since steam engines are external combustion engines, you can use an air compressor to test run them, without having to hook up the boiler. This saves a lot of time. You don't have to mount the boiler, rig it all up, waiting for the water to boil, just to debug mechanical issues.
The turbine runs at around 20 -30psi, and this little air brush compressor can simulate the steam. If you use a larger compressor, set it to 20psi for the test. Press the air compressor nozzle into the steam pipe, and blast it with air. Test run the turbine on air, check to make sure that the sprockets and chains are functioning properly, as well as the clutch and steering brakes - you can move the the linkages by hand, before setting up servos.
Step 11: Control Freak
Now that you've proven that it runs on air, and can be controlled by hand, it's time to set up the Radio Control. First make sure that the servos are installed correctly and functioning properly. I found the clutch to be a bit sticky, so I used a Futaba high torque servo. The steering servo works just fine using a standard Futaba servo.
Make sure that the linkages for the clutch and brakes are adjusted to the correct length. The brake pads should not be touching the disc when the servo is in the center position. The Clutch servo should also be centered. You can adjust the length of the servo linkages, and/or the servo horns, to insure that everything lines up.
Step 12: Making the Boiler Mount
For the boiler bracket, I used these K&S Aluminum sheets again. To bend them, use a table vice, and a bit of force will bend these to shape. They are plenty strong for the purposes here, but not so hard that you can't bend them by hand. Try making nice 90 degree bends, and cut to size with Dremel grinder discs.
Once bent to what you need, drill mounting holes for the boiler and attach it securely. Do not use thread locker for this.... these screws will get super hot!. Once secured, attach it to the chassis temporary - you will need to take out the bolts again to mount the gas tank later.
Step 13: Plumbing
Overview: This step explains how to solder and connect the pipes from the boiler to the turbine.
The Jensen turbine's nozzle is quite large of a diameter, much bigger than the Cheddar pipes. So in order for the pipes to fit, I had to use a coupling that fits between the two. Luckily, K&S makes a tubing variety pack. Sorting through it, I was able to find a piece of tubing that was just the perfect size, snug fit on both side. Silver solder the end of the Cheddar boiler pipe, to the coupling pipe, and to the turbine nozzle.
Note about soldering steam pipes
These model boilers get super hot (duh) so you need to use silver solder, otherwise when steaming up, the solder will melt. Believe me, it WILL melt your normal plumbing pipe solder. Use a torch like one pictured in the tools step, and not one of the small ones. You need to heat a big area evenly, so the small torches won't work.
Tricks for bending pipes:
Copper and brass tubing will buckle when you bend them, like straws. However, here are a couple of tricks:
1) Heat the tubing with a torch, don't melt it, but get it red. Cool it, and it then becomes very flexible and easy to bend.
2) If it is still too hard to bend to shape, you can use sand or salt. Tape up one end of the tube with a piece of tape, fill it with sand or salt, tape up the other end. This will help prevent the tubing from buckling since the sand/salt inside occupies the space. You still need to pre heat the pipe, doing this trick to normal pipes will still cause buckling... this is just an extra precaution. I was able to make the bends for this tank without using this trick.
After the pipe is completed, apply a small amount of taflon tape and connect it to the boiler. The jet nozzle fits into the turbine, and you want to get it as close to the turbine blades as possible without touching. Secure the nozzle by the set screw.
Once completed, give it another test run with the air compressor. Now you can just stick the compressor nozzle into the boiler's filler hole, and run it on air. The boiler's pressure gauge at this point will show you the pressure as well. Check for leaks in the fittings of the pipe.
Tricks for checking leaks:
Apply a tiny bit of dish washing soap mixed with water. Apply a few drops over the suspect areas where leaks can occur - around fitting ends etc. If there is a leak, you will see small bubbles forming / foaming. It is best to test this out before actually steaming! At this point you want to double check to make sure that all of the mechanics works well under air power.
Step 14: Connections
So now it's time to connect it all together.
First, connect the servos to the receiver. Connect the clutch servo to CH1, and the steering servo to CH2. This will give you basic throttle and steering ability on the transmitter. Plug the Battery to the On/Off switch. Then from the other end of the switch, plug the connector to the the receiver slot marked "BAT". If you purchase a new radio, there will be instructions on how to do this. However, once you have it in your hands, you'll soon realize that things really only plug in one way.
Push the battery pack to the space under the boiler, and use Velcro tape to secure it. Turn on the transmitter first, than the receiver, and test and make sure that both servos are working properly. At this point set you transmitter's trim and end point adjustments if needed - review your manual for your radio gear for how to do this step. This basically just sets where the center position is for the servos, and how far they can rotate. Make sure that the servos pushes/pulls the clutch, and steering brakes, far enough to work, but not too far to over torque it, or it may strip the gears inside of the servo.
Next, connect the burner to the boiler, it should be a snug fit. Run the gas pipe to where the front of the chassis, where the gas tank will sit. Bend the pipe gently until it contours the shape around the boiler. Connect the gas pipe to the gas tank to check the gas pipe for a proper fit. Be careful not to loose the sealing O-ring.
Adjust the gas tank nozzle. You should have a bit of a gap, because this is where air gets mixed with the gas for the fire. Follow the boiler/burner's instructions for this step, but it's basically a trail and error process, once you start steaming up and figure out how to get the hottest burning fire inside of the boiler.
Step 15: Making the Gas Tank Mount
The Turbine Tank now just need the gas tank to be mounted, so that it doesn't slide around and dislodge the burner from the boiler, and set the tank on fire :)
For this mount, I used sheet metal from the hardware store. This sheet metal is perforated, I have no idea what this was intended for. Cutting sheet metal is pretty easy with a pair of sheet metal shears. Put on some gloves for this step, edges of the sheet metal can be razor sharp after cutting. You can use a piece of paper as a template to make what you want first. But for this mount, it's pretty easy to just cut the sheet metal to shape without a template.
After bending it to shape by hand, paint it with BBQ spray paint. This piece does get pretty hot, since it will be connected to the boiler mount.
I also wanted a skull on the front of the turbine tank. But since I don't have.... say a laser cutter... I had to use a slightly lower tech approach. I cut a thin piece of aluminum with scissors, and couldn't get the fine detail that I wanted, but it turned out ok. I painted it with some spare paint laying around the garage, and then drilled tiny holes to mount it to the perforated sheet metal. I attached it with brads - found at a art/crafts store in the scrapbook section. Of course this is just cosmetic, you can add whatever you like to the tank at this point, or do a complete body work for it. Just make sure that you don't put plastic around high heat areas, or cover up the air supply for the burner etc.
To attach the gas mount, sandwich it between the boiler mount and the sides of the chassis, and reattach with a nuts and bolts.
Step 16: Securing the Gas Tank
To pad the gas tank and securely hold it in place, I used this..... actually I don't know what this rubbery thing it is used for, except that it was found in the plumbing section of the hardware store. It's some sort of a cap for large PVC pipe? I cut off parts of it and pushed it in to place. The gas tank fits nicely with this setup.
Next, attach the gas tank to the burner pipe for good, and double check that it is securely held in place.
Step 17: New/Old Treads
The newer version of the Blizzard has tread "paddles" on every OTHER section of the tread. The older version has these paddles on every section.
Why should you care, you ask? Well look at this video fitted with the newer treads, as compared to the older treads on the intro step.
New Style Treads
Bouncy bouncy! I even cut the tread paddles down to try to get rid of it, but it's still quite bouncy. The reason is that the peddles are basically little steps that the tank has to climb over. While this works great for snow, on flat hard ground, it's not the best system.
Old Style Treads
The older style treads, with paddles on every section, works much nicer on flat surfaces, since it's riding on those paddles the entire time. I looked into Kyosho's spare parts site, and they do not sell or produce the older style treads anymore :( So while shopping for your Nitro Blizard chassis, look for the older style treads - if you are looking to run mostly on flat and hard ground.
Picture of the tread comparison below
Step 18: Running the Turbine Tank
Here is a quick break down of how to run the turbine tank. It's quite simple as compared to steam piston engines.... there is no oil needed, so no mess dealing with oily steam exhaust, steam oilers, condensers and such. The steam comes through the turbine clean, and the exhaust is just water.
1) Add water to the boiler. Use a small funnel (usually supplied with these boilers) and add distilled water. The reason for using distilled water over tap or spring water, is that it won't cloud up the sight glass, or leave minerals that may clog up your boiler and pipes. You can purchase distilled water in most super markets that carries spring water, and cost the same as regular spring water. Add the water slowly and fill it until it reaches to the top of the sight glass. Don't over fill the boiler, you need some space for the steam to build up :)
2) Using a lighter, place the flame right on the opening of the stack. Slowly turn on the gas, less than a 1/4 turn, and you will see the fire from the lighter get "sucked" in to the stack. You can now adjust the gas valve to desired heat. You will hear the sound like a small roar when it is lit. If it goes out, it sounds like a leak - something like a leaking basketball or tire. The fire will not be visible, but you can feel the heat with your hands several inches over the top of the stack. Once it's fired, you have to wait for the water to boil, which should take around 5-10 minutes. Make sure that the steam valve is closed while it is building up pressure.
3) While waiting for the water to boil, turn on the radio transmitter first, than your receiver. Check to make sure that servos are working.
4) Once the pressure gauge reaches about 20-30 psi, it's time to run the tank! Open the valve to let the steam power the turbine, you will hear a sweet spin up sound, as the turbine powers up. The pitch changes as the turbine's RPM changes. Let it spin up and control the clutch to go forward. Check to make sure that you can go forward, back, and turns in both directions. IF there are any issues, turn off the gas first, let the steam vent totally out, and the boiler and pipes cool down, before attempting to check out the issue. I recommend wearing gloves when turning on/off the steam valve, as over time it will become hot enough to cause blisters to your fingers.
5) Once again, do not temper with the safety valve! Also make sure that you don't run the boiler dry! At full burner, this particular boiler will use up all of the water within about 10 minutes. Watch the sight glass and turn off the gas, before the water line drops below visibility on the sight glass. If you burn it dry, you risk destroying the boiler!
5) Have fun and be safe... it's really fun to drive around, and a great climber, but don't tip it! Remember you have pressurized steam, not to mention a contained fire, strong enough to boil water very quickly.
6) Be prepared for an excuse, when your neighbors asks you if you've been practicing dentistry from your garage.